TWI500013B - Liquid crystal display panel and liquid crystal display apparatus - Google Patents

Description

Liquid crystal display panel and liquid crystal display device

The present invention relates to a liquid crystal display panel and a liquid crystal display device.

With the advancement of technology, flat display devices have been widely used in various fields, especially liquid crystal display devices, which have gradually replaced traditional cathode ray tube display devices due to their superior characteristics such as slimness, low power consumption and no radiation. Applied to many types of electronic products.

Conventional liquid crystal display devices have a system common voltage, and the system common voltage is generally applied to a common electrode. Wherein, the common voltage of the system is a voltage value corresponding to the opposite ground end of the liquid crystal molecules in the liquid crystal display device. When a data line is driven at a system common voltage value, the liquid crystal molecules have a voltage difference equal to zero, so that liquid crystal molecules are not turned. However, the common voltage of the liquid crystal display device of the prior art is generally a constant current voltage, which does not change during the process in which the display device is driven to display an image.

It is an object of the present invention to provide a liquid crystal display panel and a liquid crystal display device which are different from the prior art and which have a variable system common voltage value and which can adjust the voltage value in response to the displayed image frame. For example, the system common voltage value can be adjusted in time to reduce or improve the image imprinting of the display image after the liquid crystal display device displays an image for a long time. (image residual) phenomenon.

To achieve the above object, a liquid crystal display panel according to the present invention has a variable system common voltage, and the system common voltage varies between 10 millivolts and 1 volt.

In an embodiment, the time point of the common voltage variation of the system includes a first time point and a second time point, and the time interval between the second time point and the first time point is between 1 second and 3600 seconds.

In one embodiment, a driving module drives the liquid crystal display panel to display an image frame having at least one black grid region and at least one white grid region, wherein the black grid region has a first brightness change curve, and the white grid region has a first The two brightness change curves, the black grid area and the white grid area, respectively have a DC residual common voltage value.

In an embodiment, the driving module adjusts the common voltage of the system to the brightness change curve at a first time point, and the DC residual common voltage value corresponding to the curve slope is larger, and at a second time Point, the system common voltage is adjusted to the same brightness change curve, the curve slope is smaller than the corresponding DC residual common voltage value.

In an embodiment, the driving module adjusts the common voltage of the system to the brightness change curve in a third time point, and the DC residual common voltage value corresponding to the curve slope is larger, and is in a fourth time. Point, the system common voltage is adjusted to the same brightness change curve, the curve slope is smaller than the corresponding DC residual common voltage value.

To achieve the above objective, a liquid crystal display device according to the present invention includes a liquid crystal display panel, a driving module, and a backlight module. LCD The panel has a variable system common voltage, and the system common voltage varies between 10 millivolts and 1 volt. The driving module drives the liquid crystal display panel to display an image screen. The backlight module is opposite to the liquid crystal display panel.

As described above, since the liquid crystal display panel and the liquid crystal display device according to the present invention have a variable system common voltage, the common voltage variation of the system is between 10 millivolts and 1 volt. Accordingly, the liquid crystal display panel and the liquid crystal display device of the present invention have different system voltage values and are different from the prior art, and the voltage value can be adjusted in accordance with the displayed image screen. In an embodiment of the present invention, the system common voltage of the liquid crystal display device can be adjusted to a luminance residual curve in the first time point, and the DC residual common voltage value corresponding to the curve slope is larger, and is At the second time point, the common voltage of the system is adjusted to the non-DC residual common voltage value corresponding to the curve with the smaller slope of the curve. Also. The voltage value after the common voltage modulation of the system may be in addition to the DC residual common voltage value of the black grid region or the DC residual common voltage value of the white grid region, and may also be between the two. In this way, the liquid crystal display device of the present invention can reduce or improve the liquid crystal display device after displaying an image for a long time by adjusting the common voltage of the system, and the variation range is between 10 millivolts and 1 volt. The image of the image (image residue) that occurs in the image is displayed.

Hereinafter, one of the preferred embodiments of the present invention will be described with reference to the related drawings. A liquid crystal display panel and a liquid crystal display device, wherein the same elements will be denoted by the same reference numerals.

Please refer to FIG. 1, which is a schematic diagram of a liquid crystal display device 1 according to a preferred embodiment of the present invention.

The liquid crystal display device 1 includes a liquid crystal display panel 11, a driving module (not shown), and a backlight module 12. The backlight module 12 is disposed opposite to the liquid crystal display panel 11 and emits light through the liquid crystal display panel 11, so that the liquid crystal display panel 11 can display an image frame.

The liquid crystal display panel 11 has a variable system common voltage, and the common voltage of the system ranges from 10 millivolts (mV) to 1 volt (V). The system common voltage of the liquid crystal display panel 11 is a voltage value corresponding to the ground terminal (generally a common electrode) of the liquid crystal molecules on the liquid crystal display device 1. When a data line is driven by the system common voltage, the liquid crystal molecules have a voltage difference equal to 0, so that liquid crystal molecules are not turned.

The driving module is electrically connected to the liquid crystal display panel 11 and can drive the liquid crystal display panel 11 to display an image frame. The driving module is electrically connected to the liquid crystal display panel 11 by a plurality of scanning lines and a plurality of data lines (not shown). The driving module can include a timing control circuit (T-con), a data driver, and a scan driver (not shown). The image displayed on the liquid crystal display panel 11 by the driving module can be, for example, a long-time display (for example, the same image is displayed for several days), and can be, for example, a black and white checkerboard screen. As shown in FIG. 2, the black and white checkerboard screen has at least one black grid area B and At least one white space W. Here, a black grid area B having a complex interlace and a complex white space area W are taken as an example.

Hereinafter, in detail, how to adjust the common voltage value of the system in time to reduce or improve the image imprinting (image residual) phenomenon that occurs when the liquid crystal display device displays an image after a long time.

Please refer to FIG. 3 , which is a flow chart showing the steps of a method for reducing the image imprinting of the liquid crystal display device 1 according to a preferred embodiment of the present invention.

The method for reducing the image imprinting of the liquid crystal display device of the present invention cooperates with a liquid crystal display panel 11 and may include steps S01 to S03. However, before performing step S01, some measurements are required to understand the characteristics of the liquid crystal display panel 11, and the above steps are performed using this characteristic.

The reason why the image display (image remnant) is likely to occur after the image display panel 11 is displayed for a long time (that is, the black and white checkerboard screen of FIG. 2) is that when the black and white checkerboard screen is illuminated for a while and then cut back to a gray screen. Under normal circumstances, the original black grid area B and the white grid area W should all display gray, but the brightness of the black grid area B becomes brighter (not gray enough), while the brightness of the white grid area W becomes It is darker, thus causing uneven brightness between the black space B and the white space W in the display screen, so that the display screen still displays a faint checkerboard pattern. Therefore, before performing the above steps, it is necessary to separately understand the trend of the brightness change of the black grid area B and the white grid area after the black and white checkerboard screen is illuminated for a period of time and then switch back to the gray screen, as the subsequent drive module control. in accordance with.

After measurement, one of the black and white checkerboard screens, the black grid area B and the one white grid area W corresponds to a first brightness change curve and a second brightness change curve, respectively. Wherein, the first brightness change curve and the second brightness change curve are obtained by first displaying a gray scale image and respectively measuring the gray scale brightness of the black grid area B and the gray scale brightness of the white grid area W, and then switching to black and white After a period of time, the checkerboard screen is cut to a gray screen and the gray scale brightness of the black grid area B and the gray scale brightness of the white grid area are respectively measured, and compared with the brightness of the first step, thereby obtaining The first brightness change curve of the black grid area B and the second brightness change curve of the white grid area W. In this embodiment, the first brightness change curve has a similar change trend with the DC residual voltage (RDC) corresponding to the black cell area B, and the second brightness change curve corresponds to a DC of the white space area W. The residual voltage has a similar trend, that is, the DC residual voltage has a positive correlation with the change in brightness of each cell. In addition, the gray scale value of the black grid area B of the embodiment is the lowest gray scale value of the liquid crystal display panel 11 (taking the 0 gray scale as an example), and the gray scale value of the white grid area W is one of the liquid crystal display panels 11 . The highest grayscale value (taking 255 grayscale as an example). Of course, in other implementations, the grayscale value of the black grid area B may also be the highest grayscale value of the display panel, and the white grid area W may also be the lowest grayscale value. In addition, the grayscale value of the gray screen is between the highest grayscale and the lowest grayscale of the liquid crystal display panel 11. Here, the grayscale value of the gray screen is taken as an example of 128 grayscale.

Referring to FIG. 4, it is a schematic diagram of the first brightness change curve L1 and the second brightness change curve L2 corresponding to the black space area B and the white space area W of the present invention. Among them, the ordinate is brightness and the abscissa is time (seconds).

It can be seen from FIG. 4 that the first brightness change of the black cell area B of this embodiment is changed. When the curve L1 is about 175 seconds, the brightness curve starts to rise rapidly, but after the time exceeds 230 seconds, the brightness of the black grid area B does not change much (close to saturation). In addition, the brightness of the second brightness change curve L2 of the white space area W starts to rise slowly after 175 seconds, and as time continues to increase, its brightness continues to increase. In particular, the first brightness change curve L1 of the black cell area B of the present embodiment has a characteristic that the brightness changes rapidly, and the second brightness change curve L2 of the white space area W has a characteristic that the brightness gradually rises. However, for example, under the characteristics of different materials, the brightness characteristics of the black grid area B and the white grid area W of the liquid crystal display device 1 may have opposite conditions, that is, the black grid area B may correspond to the second brightness change curve L2. And the characteristic that the brightness rises slowly, and the white space area W corresponds to the first brightness change curve L1, and has the characteristic that the brightness rises rapidly, which is not limited herein.

Then, the image imprinting improvement method of the present invention is started. As shown in FIG. 3, the step S01 of the method for reducing the image imprinting of the liquid crystal display device 1 of the present invention is: driving the liquid crystal display panel 11 to display an image frame, wherein the black grid area B and the white space W respectively correspond to an optimised common voltage. Here, the DC residual common voltage value is the common voltage value of the liquid crystal display panel 11 when the liquid crystal display panel 11 does not have a DC residual voltage under ideal conditions. In addition, the black cell region B has, for example, a first DC residual residual voltage value, and the white cell region has, for example, a second DC residual residual voltage value. Among them, the no-DC residual common voltage value refers to a common voltage value when the flicker is optimized (ie, small or not). Here, the flicker optimization is not just It means that there is no flicker at all, but it includes, for example, that the human eye does not feel the flicker. The brightness of the display screen does not occur when the display panel is driven by the gray voltage of different polarities by adjusting the common voltage of the liquid crystal display panel 11 (for example, the gray scale voltage of the black surface or the gray scale voltage of the white screen). The phenomenon of flickering, the system common voltage adjusted at this time is called the DC residual common voltage value. Here, the DC residual common voltage value is a preferred value, not an optimum value. The demander can obtain a better common voltage value of the better common voltage value due to the assistance of the experience or the measuring instrument. In this embodiment, the absolute value of the difference between the first DC residual common voltage value corresponding to the black grid region B and the second DC residual residual voltage value corresponding to the white grid region W is between 10 millivolts (mv) and Between 1 volt (for example 150mv). In addition, according to the conventional practice in the art, when the predetermined system common voltage of the liquid crystal display device 1 is to drive the liquid crystal display panel 11 in 128 gray scales, the common voltage value at the time when the flicker phenomenon of the display screen is the smallest is a constant value.

After obtaining the first DC residual common voltage value of the black grid area B and the second DC residual common voltage value of the white grid area, proceeding to step S02: adjusting the system common voltage to a first time point t1 In the brightness change curves, there is no DC residual common voltage value corresponding to the larger slope of the curve. In this embodiment, as shown in FIG. 4, in comparison, the brightness change curves are the first brightness change curve L1 of the black cell area B and the second brightness change curve L2 of the white space area W. Among them, the curve with a larger slope indicates that the brightness curve has a large slope when there is a significant change. In the present embodiment, the curve having a larger slope is the first brightness change curve L1 of the black grid area B in which the brightness curve rapidly changes in the black and white inversion area (area A), The smaller slope of the curve is the second luminance change curve L2 of the white space W which changes slowly in the luminance curve. Therefore, when the driving module drives the liquid crystal display panel 11 at the first time point t1 (for example, the 175th second in FIG. 4), the system common voltage of the liquid crystal display device 1 is adjusted to the first brightness variation curve of the black grid area B. The first DC residual common voltage value corresponding to L1.

Then, step S03 is further performed: at a second time point t2, the system common voltage is adjusted to the non-DC residual common voltage value corresponding to the smaller one of the brightness change curves. Here, as shown in FIG. 4, the curve having a smaller slope is a slower change in the brightness curve, that is, the second brightness change curve L2 of the white space W. Therefore, when the liquid crystal display panel 11 is driven at the second time point t2, the driving module can adjust the system common voltage of the liquid crystal display device 1 to the second DC residual residual corresponding to the second brightness change curve L2 of the white space W. Voltage value.

The absolute value of the difference between the first DC residual residual voltage value corresponding to the black grid region B of the present invention and the second DC residual residual voltage value corresponding to the white grid region W is between 10 millivolts (mv) and 1 volt. Therefore, in the modulation of the common voltage of the system of step S01 and step S02, the variation range of the common voltage of the system is still between 10 millivolts and 1 volt. In addition, the voltage value after the common voltage modulation of the system may be in addition to the DC residual common voltage value of the black grid area B or the DC residual common voltage value of the white space area W, and may also be between the two, and No special restrictions are imposed.

In addition, please refer to FIG. 5, which is a flow chart of another step of the method for reducing image imprinting of the liquid crystal display device 1 according to a preferred embodiment of the present invention.

As shown in FIG. 5, the method for reducing the image imprinting of the liquid crystal display device 1 may further include step S04 and step S05.

In step S04, at a third time point t3, the system common voltage is adjusted to the non-DC residual common voltage value corresponding to the curve having the larger slope of the brightness in the brightness change curve. Here, when the driving module drives the liquid crystal display panel 11 at the third time point t3, the system common voltage is again adjusted to the first DC residual common voltage value corresponding to the first brightness change curve L1 of the black cell area B.

Next, in step S05, at a fourth time point t4, the system common voltage is adjusted to the non-DC residual common voltage value corresponding to the smaller one of the brightness change curves. Here, when the driving module drives the liquid crystal display panel 11 at the fourth time point t4, the system common voltage is again adjusted to the second DC residual common voltage value corresponding to the second brightness change curve L2 of the white space W.

In other words, step S04 and step S05 are repeated steps S02 and S03. The system common voltage for driving the liquid crystal display device 1 is repeatedly adjusted in such a manner as to drive the liquid crystal display panel 11 to display a black and white checkerboard screen.

Please refer to FIG. 6 , which is a schematic diagram showing the brightness change curves of the black grid area B and the white grid area W of the display screen when the system common voltage of the liquid crystal display device 1 is adjusted at different times. The V _COM1 is the first DC residual common voltage value corresponding to the black cell area B of the embodiment, and V _COM2 is the second DC residual common voltage value corresponding to the white space W of the embodiment.

As shown in FIG. 6, in the above process of driving and modulation, the first time The time interval between the point t1 and the second time point t2 is T1, the time interval between the second time point t2 and the third time point t3 is T2, and so on. The time interval T1 to the time interval T4 may have different times, and each time interval (T1~T4) may be between 1 second and 3600 (1 hour), respectively.

Referring to FIG. 4 again, as can be seen from FIG. 4, since the brightness change of the black grid area B and the brightness variation trend of the white grid area W are different, the brightness variation of the black grid area B and the white grid area W is uneven. Therefore, the image is imprinted. Therefore, the present invention adjusts the brightness of the black grid area B and the white grid area B by changing the system common voltage of the liquid crystal display device 1 at different time points. In addition, as shown in FIG. 6, at the time point t1, since the first brightness change curve L1 of the black cell region rises rapidly, the system common voltage value is adjusted to the first DC residual residue corresponding to the first brightness change curve L1. The common voltage value V _COM1 , therefore, after the time point t1, the brightness of the black grid area B (curve L1) remains almost unchanged, while the brightness of the white grid area W (curve L2) slowly increases; in addition, at time point t2 Then, the common voltage value of the system is adjusted to the second DC residual common voltage value V _COM2 corresponding to the second brightness change curve L2 of the white space area W. At this time, after the time point t2, the brightness of the black grid area B is fast. Rise (curve L1), while the white grid area W maintains the previous brightness (curve L2 remains almost unchanged); in addition, after a period of time T2, at time point t3, the system common voltage value is adjusted to the first brightness V _COM1 corresponding to the change curve L1. At this time, after the time point t3, the brightness of the black grid area B (curve L1) is almost unchanged, while the brightness of the white grid area W (curve L2) is slowly increased, and so on. . Continuously adjust the common voltage value of the system to make the brightness change of the black grid area B and the white grid area W close. Since the brightness trends of the black grid area B and the white grid area B are close, the human eye does not feel the difference in brightness between the two, so the black and white checkerboard pattern is not visible. In addition, the time point shown in FIG. 6 is only t6, which does not mean that the common voltage value of the limiting system of the present invention can be stopped only when it is adjusted to the time point t6, but the adjustment is continuously repeated.

Therefore, by adjusting the common voltage value of the system in a timely manner, the image printing (image residual) phenomenon that occurs when the liquid crystal display device 1 displays an image after a long time is displayed can be reduced or improved.

In summary, since the liquid crystal display panel and the liquid crystal display device according to the present invention have a variable system common voltage, the common voltage variation of the system is between 10 millivolts and 1 volt. Accordingly, the liquid crystal display panel and the liquid crystal display device of the present invention have different system voltage values and are different from the conventional techniques, and the variation value can be adjusted in accordance with the displayed image screen. In an embodiment of the present invention, the system common voltage of the liquid crystal display device can be adjusted to a luminance residual curve in the first time point, and the DC residual common voltage value corresponding to the curve slope is larger, and is At the second time point, the common voltage of the system is adjusted to the non-DC residual common voltage value corresponding to the curve with the smaller slope of the curve. Also. The voltage value after the common voltage modulation of the system may be in addition to the DC residual common voltage value of the black grid region or the DC residual common voltage value of the white grid region, and may also be between the two. In this way, the liquid crystal display device of the present invention can reduce or improve the display of the liquid crystal display device after displaying an image for a long time by adjusting the common voltage of the system and varying the range between 10 millivolts and 1 volt. Image impression of the image Like a residual phenomenon.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

1‧‧‧Liquid crystal display device

11‧‧‧LCD panel

12‧‧‧Backlight module

A‧‧‧ area

B‧‧‧Hague District

L1‧‧‧ first brightness curve

L2‧‧‧second brightness curve

S01~S05‧‧‧Steps

T1~t6‧‧‧ time point

T1~T4‧‧‧ time interval

V _COM1 ‧‧‧First DC residual common voltage value

V _COM2 ‧‧‧Second no DC residual common voltage value

W‧‧‧白格区

1 is a schematic diagram of a liquid crystal display device according to a preferred embodiment of the present invention; FIG. 2 is a schematic diagram showing an image of a liquid crystal display device of FIG. 1; FIG. 3 is a schematic diagram of reducing a liquid crystal display device according to a preferred embodiment of the present invention; FIG. 4 is a schematic diagram of a first brightness change curve and a second brightness change curve respectively corresponding to the black grid area and the white grid area of the present invention; FIG. 5 is a schematic diagram of a preferred embodiment of the present invention. A schematic diagram of another step of the method for image imprinting of a liquid crystal display device; and FIG. 6 is a schematic diagram showing a brightness variation curve of a black grid region and a white grid region of a display screen when the system common voltage of the liquid crystal display device is adjusted at different times.

L1‧‧‧ first brightness curve

L2‧‧‧second brightness curve

T1~t6‧‧‧ time point

T1~T4‧‧‧ time interval

V _COM1 ‧‧‧First DC residual common voltage value

V _COM2 ‧‧‧Second no DC residual common voltage value

Claims (8)

A liquid crystal display panel having a variable system common voltage, wherein a common voltage range of the system is between 10 millivolts and 1 volt, wherein a driving module drives the liquid crystal display panel to display an image image Having at least one black grid region and at least one white grid region, the black grid region has a first brightness change curve, the white grid region has a second brightness change curve, and the black grid region and the white grid region respectively correspond to There is no DC residual common voltage value. The liquid crystal display panel of claim 1, wherein the time point of the common voltage variation of the system comprises a first time point and a second time point, and the time interval between the second time point and the first time point Between 1 second and 3600 seconds. The liquid crystal display panel of claim 1, wherein the driving module adjusts the common voltage of the system to the brightness change curve at a first time point, and the curve has a larger slope. The DC residual common voltage value is adjusted at a second time point to adjust the common voltage of the system to the non-DC residual common voltage value corresponding to the curve with the smaller slope of the curve. The liquid crystal display panel of claim 3, wherein the driving module adjusts the common voltage of the system to the brightness change curve at a third time point, and the curve has a larger slope. DC residual common voltage value, and at a fourth time point, the common voltage of the system is adjusted to the brightness change curve, the curve slope is small There is no corresponding DC residual common voltage value corresponding to the one. A liquid crystal display device comprising: a liquid crystal display panel having a variable system common voltage, the common voltage variation range of the system is between 10 millivolts and 1 volt; a driving module driving the liquid crystal display The panel displays an image frame having at least one black grid region and at least one white grid region, the black grid region having a first brightness variation curve, the white grid region having a second brightness variation curve, and the black grid region The area and the white space respectively correspond to a DC residual common voltage value; and a backlight module is opposite to the liquid crystal display panel. The liquid crystal display device of claim 5, wherein the time point of the common voltage variation of the system comprises a first time point and a second time point, and the time interval between the second time point and the first time point Between 1 second and 3600 seconds. The liquid crystal display device of claim 5, wherein the driving module adjusts the common voltage of the system to the brightness change curve at a first time point, and the curve has a larger gradient The DC residual common voltage value is adjusted at a second time point to adjust the common voltage of the system to the non-DC residual common voltage value corresponding to the curve with the smaller slope of the curve. The liquid crystal display device of claim 7, wherein the driving module adjusts the common voltage of the system to the brightness change curve at a third time point, and the curve has a larger slope. The DC residual common voltage value is adjusted to a common voltage of the system in the brightness change curve at a fourth time point, and the DC residual residual voltage value corresponding to the curve slope is smaller.